"Add items from local storage" did not work properly, now have unremovable images in g2data

Recently my gallery's database became corrupted, so I deleted it and started a fresh one. I decided to start everything from scratch, deleting and re-installing the gallery2 folder and moving the old g2data folder to g2data_old to make way for a fresh g2data folder. Now that I've got a new clean install of the gallery I'd like to transfer over all my albums and photos from g2data_old. So I used the "add items from local storage" upload method. I checked all the folders corresponding to each album and added them. According to http://codex.gallery2.org/Gallery2:How_to_Add_Items it says that "if you select entire subdirectories, each subdirectory will create a new album automatically", however this was NOT true in my case. In fact, my gallery still appeared as empty despite the fact that all files and folders had been copied from g2data_old to g2data when I checked via ftp. So now I've got a bunch of images in g2data that aren't being seen by the database and I can't delete any of them through ftp because the owner is set to "apache" and I get an error about permissions if I try to delete them.

So I have 2 questions:
1. How do I delete these files from g2data so I can try adding them again?
2. When I do try to add them again, what should I do to avoid having this same problem happen again?